Saws have a long history, and from its beginning to date, handsaws have been used by many people.
Meanwhile, electric power saws, which have been developed relatively recently, are electric power tools which cut wood and others with overwhelming horsepower supported by electric power. The same applies to chainsaws powered by engines. Although the electric power saws etc. having overwhelming power, so-called power saws, and the handsaws which cut using human power only, without relying on electric or other power, are similar in that both use cutting teeth, in practice, they are considerably different in terms of concepts regarding their structures and functions, so they belong to substantially different technical fields.
FIG. 12 shows an example of a handsaw. A handsaw is generally made up of a grip 81, called a handle, and an elongated metal saw blade 82 attached to an end of the grip 81. A large number of teeth 83 are arranged on a longitudinal edge of the saw blade 82.
The handsaw shown in FIG. 10 (A), (B) is an example of the so-called ripsaw. The ripsaw is suitable for cutting wood along the grain. The ripsaw has a large number of triangular teeth 73 arranged on the longitudinal edge of the saw blade 72, and performs cutting with the distal ends of the triangular teeth 73 as cutting edges 7P. Each triangular tooth 73 has a base that constitutes a gullet or valley 7V together with the base of the adjacent triangular tooth 73.
The handsaw shown in FIG. 11 (A), (B) is an example of the so-called crosscut saw. The crosscut saw is suitable for cutting wood across the grain. In the crosscut saw, each triangular tooth 83 formed on the longitudinal edge of the saw blade 82 has sharp vertical cutting edges 83a, 83b, called “Higaki” in Japanese, provided on a pair of front and rear beveled portions on a distal end of the tooth. The vertical cutting edge denoted as 83a is in front with respect to the cutting direction D, and the vertical cutting edge denoted as 83b is at back with respect to the cutting direction D.
The vertical cutting edges 83a, 83b cut into the wood like knives, to sever the grain. The bases of adjacent triangular teeth 83 constitute a gullet 8V.
Some known crosscut saws have a cut end face 84, called “top edge” (“Uwame” in Japanese), formed by obliquely truncating a triangular tooth 83 near its distal end, and front and rear edges of the cut end face 84 serve as horizontal cutting edges 84a and 84b. The cut end face 84 and the horizontal cutting edges 84a, 84b can achieve the function of a ripsaw, or, the function of, when cutting wood, carving and scraping off, like a chisel, a part of the wood corresponding to the thickness of the saw blade 82.
Japanese Utility Model Application Laid-Open No. H6-71101 (Patent Document 1) discloses a handsaw having triangular teeth (11) to (18), which are arranged alternately in opposite orientations to face each other and are also provided with top edges (11a) to (18a). This handsaw is similar to the crosscut saw shown in FIG. 11 described above.
Japanese Patent Application Laid-Open No. 2003-117903 (Patent Document 2) discloses a saw blade which is provided with a cutting chips reservoir (7) made up of a recess (10) formed on an outer surface of a cutting tooth (2) for the purposes of preventing the spaces between respective sides of the saw and the cut surfaces of the wood from being clogged with cutting chips.
Japanese Patent Application Laid-Open No. 2013-52575 (Patent Document 3) discloses a saw blade which has teeth formed such that base portions (3B), (3B) of adjacent teeth (3), (3) are separate through the intermediary of an arcuate groove bottom surface (20) for the purposes of preventing clogging with chips.